


Growing up

by AuthorInDistress



Series: Pack Making [2]
Category: Haikyuu!!
Genre: Alpha/Beta/Omega Dynamics, No Sex, Omega Kageyama, Prequel
Language: English
Status: Completed
Published: 2016-02-12
Updated: 2016-02-12
Packaged: 2018-05-20 00:05:03
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,062
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5985637
Author URL: https://archiveofourown.org/users/AuthorInDistress/pseuds/AuthorInDistress
Summary: <blockquote class="userstuff">
              <p>Kageyama has his first heat during his Kitagawa Daiichi days.</p>
            </blockquote>





	Growing up

**Author's Note:**

> Damn Oikawa is hard to write.

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* * *

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Kageyama woke Friday morning feeling heavy in his skin, worn out and exhausted although he'd gotten a good night's sleep and hadn't gone to bed particularly late either.

He rolled onto his side with a groan, pushing himself up onto his elbows to take a peek at the clock above his bed. 6am. He sighed, pushing himself up and out from under the covers and heading downstairs in his pyjamas.

"You're up early," His mother commented when she saw him pad barefeet into the kitchen, washing the dishes that she'd used last night, "Did you want some breakfast before I head to work?"

He shook his head, his stomach hurting a lot more now that he was standing, "I feel sick ... " He mumbled instead, wrapping his arms around his torso and shutting his eyes. 

His mother frowned at him, "You don't usually get ill so suddenly, did you go to sleep late last night?" 

He shook his head, taking a seat at the table and pushing aside the flower pot to rest his head over that area instead. His mother twisted the tap off and dried her hands, heading over to feel his head.

"You don't feel warm," She muttered but as he'd never really pretended to fall ill before, she relented, "Do you want to stay home today?"

He almost agreed, thinking only of his stomach and the groggy feeling in his head, but then his mind stuttered over toward the fact that he had Volleyball practice today and that Oikawa would be practicing his serving late after school as well. 

He'd hoped to at least watch from the sidelines and to pick some of his techniques up, especially as it didn't seem likely that he'd be _taught_ anything by Oikawa any time soon. Not with how often he'd been rejected. 

"No!" He protested quickly, unnecessarily loud, "I have to go in today."

His mother smiled, shaking her head, "Volleyball, hm?" He looked away, and played with the hem of his shirt, "Well alright. But don't put the sport above your health. If you feel too bad later on, go to the nurse and ask him to call me. Okay?"

He shrugged, looking down at his lap, and she ruffled his hair. 

"Go and get ready then, if you're going to go." 

"Can I have some toast?"

She nodded and he quickly ran upstairs to change, wincing when his stomach throbbed all the more, but he still dressed in record speed in an attempt to prove to his mother that he'd be alright going to school for practice.

She still insisted in dropping him off however, saying that walking might make him feel worse, but she'd had to top the car with fuel on the way and had seen a friend of hers doing the same.

The resulting catch-up conversation had taken almost half an hour and she'd had to rush them here afterwards anyway, so now he _still_ had to run with a bad stomach despite her driving him here to stop that.

He managed to make it to class in time however and took his usual seat at the back, trying not to throw up when the pain in his stomach only worsened as the first class of the day started. 

He never really commented in lessons at school but his teacher still somehow guessed that something was wrong and practically ordered him to go to the nurse's. He left gladly, his head stabbing with pain alongside his stomach now, but the nurse only gave him some water to drink when his temperature was checked and he didn't find much change in it.

"Have a rest for a bit and we'll see how you feel later," The nurse told him, running his fingers through his hair as he looked Kageyama over again, "You do look a little pale, though."

Kageyama just nodded, taking a seat in the office and hunching over. When his lunch break came around however, he somehow felt much better and the nurse told him to get something proper to eat and to come back  _only_ if he threw up.

He immediately headed over to the gym instead, not really having much of an appetite today, and he didn't plan on spending his break choking down food when he didn't really feel like it. On the way there however, Kaname (an alpha in his class) barged into him from where he was running after a tennis ball and he slammed into the wall beside them.

His stomach lurched at that and he felt a spike of anger bubble in him when the pain heightened, "Watch where you're going!" He snapped and Kaname gave him a dirty look.

"What's with you, moody?" He snapped back, "Got your heat?"

"Drop dead," Kageyama glared at him, pushing past with a growl and quickly rushing to the gym to avoid hearing Kaname say anything else to him about heats.

As a late developer, Kageyama was one of the only omegas in his year that hadn't had his heat yet or even developed in any other way either, but he hadn't told anyone that for fear of being mocked for it. His scent was still the musky scent of a young omega though but the others his age either didn't seem to notice, or they had and had spoken about it behind his back. He felt the second was more likely considering the heirarchy of popularity in his year and the fact that he was right at the bottom.

Having your scent change during your first heat was apparently an important part of an omega's puberty because it led to attraction and to 'growing up'. Many omegas his age seemed to see it as a rite of passage and it changed how they behaved in many ways as well.

One of Kageyama's ex friends from junior high had had her first heat the second week of Middle school and she barely spoke to him anymore. Her entire personality had changed into something that he found he didn't much like and she poured far too much effort into gaining the attention of alphas and betas rather than forming friendships with other omegas.

In fact, more often than not, she treated omegas horribly and held alphas to a different standard. He tried not to be bitter about it because if that was how she wanted to live then fine, but it still stung to remember how easily she'd dropped him as a friend. He blamed her first heat for it and was incredibly scared of his own and how it may change him as well. 

Oikawa was in the gym as usual when he arrived, practicing spikes with Iwaizumi, and he wasn't acknowledged by the former when he came in to join them; having changed already in the club room. 

There wasn't a lunch time practice per say but Oikawa and Iwaizumi often spent some lunches here anyway and he'd become accustomed to coming and watching them, and maybe even practicing some of his own tosses as well. 

"Hey Kageyama!" Iwaizumi called over to him, panting, "You want me to hit some of your tosses too?"

Oikawa huffed loudly at that and squeezed the volleyball in his hands, so Kageyama declined in case he created another argument between the two. He remembered hearing the shouts in the gym after he'd left three days ago, when Oikawa had been angrier than he'd ever seen him before and had lashed out. 

Iwaizumi had told him afterwards that that hadn't been his fault, and he believed him, but he still didn't want to get in the way of their friendship. Especially as his private conversations with Iwaizumi over the situation had sparked some vicious rumours that he may be interested in the other alpha, which had just made Oikawa even more furious. 

"Can I just watch?"

"No, no," Oikawa said, his voice sickly sweet in a way that meant that he was going to say something that Kageyama would hate, "I'd like to see you toss for Iwa-chan today, Tobio," He smiled, "Give me a break for a bit and I can see where you need to improve."

Oh. That - sounded decent actually. He smiled back, jumping to his feet, "Okay!"

Iwaizumi frowned at Oikawa however, and he reacted slowly to Kageyama running toward them, moving aside only to make room for another setter beside the net. 

Kageyama lifted a ball from the basket but Oikawa snatched it from him and gestured that he stand right by the net instead. He then threw it and Kageyama realised what he was doing a second before it would have been too late and he quickly tossed. 

It was too high and he winced at the poor quality of his move, watching Iwaizumi struggle to hit it with his full strength. He still managed however and it was in line, but still. He could do better.

"Ah Tobio-chan," Oikawa tutted, somehow in tune with Kageyama's thoughts, "You can do better than that."

Kageyama grit his teeth and opened his mouth to reply that he knew that, but he startled when Iwaizumi slapped him on the shoulder and turned to him instead.

"Don't worry about it, just toss it a little lower next time."

He beamed, barely hearing Oikawa gag behind them, "Okay!"

The second toss was better, much better, and so was the third but by the fourth his stomach was starting to hurt again. He almost missed the sixth toss when dizziness joined in with the pain and he had to blink several times to clear his vision.

"Sorry," He said when he saw Iwaizumi frowning at him.

"If you're sick, Tobio-chan, I'll take over again ... " Oikawa threatened, tossing him another ball. 

Kageyama snapped himself out of it but the moment the ball left Oikawa's hands a waft his scent blew toward him in the breeze from outside and his head swam. The ball slipped past his outstretched hands whilst he stood there, too out of it to properly react before it hit him in the face. He fell hard and blinked out of the daze that he'd been in, staring down at his hands in shock that he'd missed.

He heard a bark of laughter from Oikawa but it was cut short by a cry of pain and then Iwaizumi was helping him up.

"You okay, Kageyama?" He asked, placing a hand on his shoulder and Kageyama felt himself leaning into that touch with a sigh.

"I don't know ... " He shut his eyes, sagging, and Iwaizumi held him steady with a grunt, "My stomach - "

His thighs felt wet now and he panicked, wondering if he was bleeding somehow, and Iwaizumi's hands left him to help him stand. He almost fell again, however, when he suddenly felt Oikawa grab him by his shirt and yank him forwards. He slammed into his chest and that same scent from before overwhelmed him, making him whimper aloud. He clutched at Oikawa's shirt and squeezed his eyes shut. 

"Should you call his mother?" Oikawa half asked, half told Iwaizumi and there was a moment when they were then left alone as Iwaizumi left to go get the number. 

"It hurts," Kageyama choked out with a moan, his nose clogged with Oikawa's scent and it was making him shake all over.

"Yeah, you're having your heat," Oikawa explained, sounding a little too serious before pushing Kageyama away for a second and grabbing his face by the cheeks, squishing them together, "Such a _grown_ Omega now ..." He grinned, using the baby-voice that he so often used on Kageyama during their practices. 

"I don't want to grow up," Kageyama said pitifully, still shaking. 

Oikawa laughed and it echoed around them, "No choice in that I'm afraid Tobio-chan," He pulled him closer again, pressing a hand to the back of his head to keep him there, "Just breathe in my scent, it'll help."

"Won't we bond?"

"No you useless idiot, you need to have sex for that to happen."

"Oh." His voice sounded far too small to his ears and he was glad when Iwaizumi ran back into the gym with Kageyama's phone.

"What's your password, Kageyama?" He asked, putting a hand on his back to get his attention but all his touch did was make Kageyama keen and arch toward it. 

He removed it quickly and said something to Oikawa over his head that he couldn't quite hear over the rushing in his ears and the overpowering alpha scent from the both of them.

"The password, Kageyama. I need to call your mother."

"Get it from the office, we've got emergency numbers," Oikawa suggested.

"The coach has the key to that and I couldn't find him. Move him away so he can at least think."

Oikawa pushed Kageyama back again and he squeezed his eyes shut, shaking like a leaf.

"Kageyama I need to know your password."

He blinked his eyes open, squinting past the pain and nausea, "One - " He swallowed, "One, two, three, one."

"Okay, good," Unlocking his phone, Iwaizumi searched through his contacts to find his mother's number and dialed it, walking away to make the call. 

Oikawa pulled Kageyama back again, chuckling, "I know your password now, Tobio- _chan_ ," He said into Kageyama's hair.

"Okay. I don't have anything secret on it though."

Oikawa sighed, "Of course you don't. You're too boring."

"Sorry," Kageyama whispered, at a loss of what to say to that but Oikawa just sighed again, "What happens now?"

"You go home and leave me alone."

"Oikawa - "

"How am I supposed to know?" Oikawa muttered angrily, running a hand through Kageyama's hair softly, "I'm not an omega. Your mother will know what to do, she'll come get you."

Iwaizumi jogged back toward them again, shutting the phone off and sliding it into Kageyama's pocket, "She said to wait for her in the car park," He informed them, "I'll go get his stuff."

Oikawa nodded, his chin hitting Kageyama's head with how he'd bowed over to cover him as much as he could, "Such a good sempai Iwa-chan is," He said, making his voice croaky for some odd reason but Iwaizumi seemed to understand the joke and laughed. 

"I'm not the one hugging him," Was all he said in reply however before leaving them both again to collect Kageyama's stuff from the club room.

"Come on, useless," Oikawa then said, lifting Kageyama with a groan until he rested on his hip like a toddler. It was a mortifying position but at the moment he couldn't bring himself to care, "There really _must_ be nothing in your brain, you're so light."

"Brains don't make you heavy," Kageyama told him matter-of-factly, resting his head on Oikawa's shoulder and shutting his eyes as he was carried outside, "Muscles do."

"You do realise you've just implied that you don't have those either."

"I don't," Kageyama agreed, "But I will."

"Yeah yeah, whatever." Oikawa murmured, "I hope you do. It'll make beating you so much more satisfying."

"We're on the same team." Kageyama reminded him and he was jolted for that, making him cry out when his stomach pulsed in pain as it hit Oikawa's elbow.

"Serves you right," Oikawa muttered but he also sounded a little apologetic and Kageyama smiled, especially as he also let him down gently once they reached the car park. 

His mother obviously wasn't here yet and he was starting to feel itchy all over. The wetness between his thighs seemed to feel like it was spreading and he resisted the urge to look down at his shorts to see if there really was a stain or not.

Oikawa kept holding him close, sitting beside him on a bench, and his shaking subsided slightly as he relaxed but as soon as Iwaizumi returned with his bag and uniform, it started up all again. 

"I don't like this," He moaned, clutching his stomach.

"No one likes growing up." Oikawa said.

"You don't get heats," Kageyama countered with a pout.

"Yeah I gather they suck," He was grinned down at then, "Better hope yours are short though, or else you'll miss out on a lot of practice." He must have looked distraught at that because Oikawa laughed again. 

Iwaizumi slapped the back of his head for it however, "Leave him alone, dumbass. You're two years his senior, act it."

"That hurt, Iwa-chan!" Oikawa moaned, holding his head and Iwaizumi smirked.

"Good."

A few minutes later his mother's car pulled up into the lot and she quickly stepped out to come toward them. 

Oikawa stood and helped Kageyama up, watching with his hands in his pockets now as she checked her son over.

Seeing his mother here somehow made everything seem a whole lot worse and he felt a weird sort of shame fill his chest when she glanced down at his shorts and pressed her lips together. The feeling filled him entirely the longer that she kept silent until he ended up bursting into tears.

"I'm sorry," He sobbed, wondering why he was and how to stop it, because Oikawa was watching and he never usually cried so easily, why was this happening? "I didn't mean to ... "

"Oh don't be silly, Tobio," His mother hugged him close, "You haven't done anything wrong, it's alright. Come on, let's take you home."

She then turned to Oikawa and Iwaizumi and smiled, "Thank you for taking care of him," She said, gently pushing Kageyama toward the car, before quietly adding, "I see why he looks up to you two so much."

Kageyama allowed himself to be led away, looking back to see Oikawa making a face at whatever his mother had said and Iwaizumi shoving him to stop and to get back into the gym.

Now that their scent was gone, he settled in the car, and felt only the nausea from before and a thrumming pain in his lower stomach. It cramped as he sat but the shaking and dizziness left as suddenly as it had arrived, leaving him slightly breathless and weak.

His mother stopped at a pharmacy on the way home to buy some medicine for him and also at the shops to buy some new underwear as well. It was an omega-brand, to be worn while on heat to soak up any fluids that may stain their clothes, and he looked through the bag curiously while they drove off. 

"Can I get pregnant now?" He asked, his fingers digging into the underwear package. 

"You're able to now yes, but obviously you shouldn't at this age," She turned into their street, "Your heat's a time where your body is ready for a baby, when an alpha or a beta can impregnate you, and when you get older sex during your heat is what will cause that."

His cheeks reddened and he gagged a little, making her laugh. 

"I think it's time you know, but we'll save the rest of this talk for later okay?" She parked and he climbed out, taking the bags that she'd brought out with him, "First, go take a shower and I'll make you some pork curry. Sound good?"

He nodded, waiting for her to open the door, before coming inside and heading upstairs immediately. She called him down again however and made him take some of the tablets that she'd brought to help with the pain, before unwrapping the new underwear and sending him upstairs again. 

"Take as long as you need, warm water will make you feel much better."

"Can I have a bath instead then?"

"You can do if you want, but it'll take a while to fill up the tub and your stomach hurts. It's up to you."

Standing in the shower didn't sound too good either so he started filling the tub whilst he heard his mother turn the stove on. 

When he lifted his shirt off to strip, Oikawa's scent seemed to be stuck to it and he swooned against the door before coming to his senses and tossing it into the laundry basket. He did the same for his shorts before throwing his underwear into the bin instead. It was soaked through and really didn't seem salvageable. 

He'd learnt this in a puberty lesson once and he knew that it was a bodily fluid that his body created, to self lubricate him during his heat, but he didn't like the smell of it and it had covered his underwear entirely.

The tub was almost full by the time he was done inspecting his body then and he shut the door and lowered himself into the water slowly. All of his fears of growing up reawakened as he soaked in it however, and he hugged his knees with a sigh, shutting his eyes and trying to relax despite his thoughts.

He rest his chin on the tip of his knees and inhaled to calm himself down but it had the opposite effect when he realised that his scent had changed too; just as he'd known it would but the speed of it still scared him. He smelled ... _sweet_ now. Like all the other omegas in his class.

He'd usually thought that maybe they were just wearing a perfume as some of them usually were spraying stuff on each other, but if this was how he naturally smelled now then maybe it was the same for them. 

His first hour on heat and already there was a major change. He hoped that everything else would stay the same, prayed even, because as much as he didn't mind talking to some alphas he also didn't want to start throwing himself on them either. It would also do nothing to shut down the rumours about him and Iwaizumi if he started acting like that. 

He sighed, leaning back against the edge of the tub and shutting his eyes.

"Tobio!" He flinched at the knock outside, "The curry's made and I've left the new underwear on the table for you to put away wherever you want to. I have to go back to work now okay? I'll leave the keys for you so make sure you lock the door when you come out!"

"Can't you lock it?" He called back, "And post them back into the house through the letterbox?"

"... Alright," She agreed with a sigh, "Make sure you do eat, though, okay? It's important you do, even if you don't feel like it!"

"Okay!" He shouted to let her hear him as she walked away and a minute later he heard the door shut and the jangle of keys being posted back into the house.

He lay back again then, humming under his breath. The warm water really did help with the pain and he felt much better when he finally climbed out of the tub to get to bed. He didn't bother changing, only slipped the new underwear on and grabbed a fluffy blanket to wrap around himself as he went downstairs.

He warmed a plate of the curry, taking it upstairs with him to eat in his room, and once he finished he put the plate on his desk and curled into his bed to try to sleep. As soon as he did, however, the relaxation that the warm bath had given him vanished and the pain returned all at once.

He moaned, rolling over, and heading to the bathroom to find a hot water bottle. He filled it with the kettle from downstairs and climbed into bed again, hugging it to his stomach.

He was almost asleep when his phone buzzed and he glanced down at it with a scowl. There were two texts, one from Kunimi saying _'welcome to the life of a grown omega',_ which seemed like both a warning and an actual welcome. The second was from Oikawa and it only said _'you owe me a new shirt'_ which didn't make sense at first but then he was sent a picture and he saw a wet patch over the hem of Oikawa's shirt that was circled in red in an effect.

He felt his face grow horribly warm once he realised what that patch was and he then sent a million apologies through the text to which Oikawa only repeated that he was still owed a new shirt and that he had an _'important'_ practice to get back to.

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**Author's Note:**

> Feedback is wonderful :)


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